I'm creating a client based application in HTML Application (HTA) and I would like to know if there's a object persistent library similar to python's shevle that meets the following criteria:
Should be able to read and write on file
Cross browser: should work at least on both HTA and on Firefox (through XULRunner) so that I'll be not tied to any vendor.
Written in JavaScript form
TiddyWiki is able to save itself, regardless of the browser used, though the codes that saves and retrieves files has to be refactored to meet my need.
Well, I wasn't aware that TiddyWiki has a github repository, and they organized the files by module.
I could just take the FileSystem.js file and build a nice api on top of it to simulate shelve functionality.
Related
I have read several posts on this site that ask similar questions but the key difference is they involve a client and a server. For my use, this is not the case. I am simply pasting a file directory on my computer into my browser in order to view a local HTML file, packed with CSS and some jQuery.
I've been looking around and the answers I've found are "No; a client can not write to a server", and "No; a server can not write to a client". But there is no answer to "can a client write to a client with JavaScript?"
Use case:
I'm building a webapp (website? JS app?) as a college project for a stock management tool that will be locally hosted and never connect to the internet. Sure, I could knock one together in python in a couple hours, but I wouldn't learn anything. I need to create an access a txt file containing an array of the current stock of all the items so that when the application is loaded, the user doesn't have to manually enter anything but the changes to stock levels.
Honestly, I'm a beginner at JS and JQ and I'm only going off of what makes sense based on a mix of HTML and Python that I know.
Maybe PHP would be the better option for this particular option, or maybe JS will work well enough.
You still won't be doing client-to-client, your browser will just act as though the local file system is the server using the file:// protocol which means the same rules about a "client" (the browser) cannot write to a "server" (your local file system) apply.
If you wan't to be able to write an application that can interface directly with the filesystem, then look into something like Electron which is essentially an augmented website that gives you APIs to interact with the actual computer the app is being run on, including filesystem stuff.
I'd like to have a way for a webpage -which is generated dynamically by my server- to read all the files in a specific user folder, manipulate them using javascript, within the web browser, and using them to show to the user some results (specific correlations between the data, dependent on the context and sometimes some graphs, drawn using these correlations).
Communication with the server about these data is neither required nor desired. Actually, since all the manipulations needed can be done via javascript and the files can be huge, for now I absolutely don't want that their content is uploaded to the server. Therefore there are no security risks (at least none that I can see).
Server side, I'm only interested to save the name of the folder, so that the user (who is registered) doesn't need to select the files one by one or to select them again every time a new page is dynamically created.
For now, the only hopes to find a solution that I have been able to gather are about using the Chrome FileSystem API (but I'd prefer a general solution, not dependent on a specific browser) or creating an extension that the user should install to use this feature when visiting the website (which, for me, is maybe even worse than relying on a specific browser).
So I wonder if there is a way to implement this feature using only pure javascript and HTML5 and using neither extensions nor browser dependent solutions.
Due to security reasons, JavaScript running in the browser should not be used to access the filesystem directly. But definitely you can access it using Node's fs module (but that's on the server side).
Another way is, if you let the user pick files using the <input type="file"> tag then you can use the File API to fetch the contents. But I think that is not what you are looking for.
Recommended reading: https://en.wikipedia.org/wiki/JavaScript#Security
I am trying to build a simple application for managing a database (most likely sqlite) of members of a society. The resulting app needs to be useable on windows and OSX and ideally be packaged as a single file.
My plan was to use a single HTML file that embeds all the javascript needed within the same file, which would be stored on the user's computer. The user could then simply double-click and open the page in their favourite browser, where the JS would be executed to handle the user interactions with the database and so on. On first running the sqlite database would be created on the user's machine which would persist the data and could also be backed up as needed.
My question is, how can I go about creating and modifying the database file from within the browser? Traditionally this has been a big no-no (for obvious security reasons) but looking into things like app.js and others I feel like there might be another option for achieving this simply. An option might be to have a "save/load" dialog if nothing else. The key factor is to avoid having the user install any extra dependencies like node.js etc, as this is a very simple tool.
You can create html and js desktop applications with AIR or XUL. AIR needs the AIR runtime and will be one file to install your application and XUL needs either xulrunner or Firefox to start it. You can deliver XUL applications as a zip file and run them with firefox --app application.ini.
There may be more options out there
Html5 supports both key/value and sqlite type persistence out of the box. Depending on your needs you may be to use either or both. They are mostly portable among most browsers now.
Is it possible with Javascript or jQuery to convert mp3, wav, etc. to m4r format?
Let's assume you had a library that can change the format of files.
Let's also assume you only need the application to work on current browsers that implement FileAPI or FileReference so you can have access to uploaded files (you can't have access to them without FileAPI or FileReference unless you use Flash or Java Applets or equivalent technologies).
You wouldn't be able to write the output file back to the user because JavaScript is not allowed to access the local filesystem.
Your only solution would become sending the converted file to the server and the server sending it back to you with a force download directive so that the user will be prompted to download the results.
Now back to if there were a library that can the conversion (or even native JavaScript)... I haven't heard of any. It's not impossible to build one but it is impractical and wouldn't run very fast.
Edit:
Let's not forget Node.js!
It's a backend server that uses Google Chrome's V8 JavaScript interpretor/compiler. And it runs JavaScript as a backend scripting engine.
You have access to filesystem, databases and everything if you use that (or any other backend system for that matter) and still be using JavaScript. You can use libraries too. Either written in JavaScript or libraries written in other languages that have been linked to interface with Node.js.
Edit 2:
There is a PC emulator written entirely in JavaScript. It runs binary executables if you want it to. It's called JSLinux.
If you're feeling particularly rambunctious you can grab the ffmpeg binary executable (compiled with static linking). And embed it into your application code as an uuencoded string then use JSLinux to execute the commands and grab the results.
Indeed, it is possible doing this on the client using the latest js technologies. A web-worker thread can do the work in the background. At least in Firefox and Chrome it is also possible to read ("upload in memory") and write ("download from memory") files using the new W3C File API, see here.
I managed to read files via drag&drop from and within the client using google's GWT which in the end is plain javascript, so it must also be possible to do it "natively".
Besides that, the conversation algorithm of course has to be implemented in a javascript web worker to avoid blocking the gui. This should be the hardest part, but not impossible, though.
You would need a backend to do this. You may want to look into the PHPExtension of FFmpeg
Trying to see if this is possible -
1.) User logs into our site
2.) Points to a directory
3.) The javascript code reads contents of the directory, shows thumbnails for any jpeg/gif in those directories. This all without uploading all the photos to the server. Kind of a semi desktop app.
Point 3 is something I have never done, is this possible for an online application to do ?
You can't do this...yet (unless you're using a prerelease of Chrome 9). There are some APIs coming down the pike that will make this possible in browsers that support them; there's a description of using them in this article.
But right now, no. To do this, you'll need to use a technology that allows local file access, such as a signed Java applet (normal unsigned ones obviously can't do this) or, on a severely limited number of platforms and browsers, an ActiveX control.
Update: Sorry, the new JavaScript APIs I mentioned above don't give you (user-granted) access to any old directory on their system. They do give you access to the file system, but it's a sandboxed file system. So you'd have to have the users move the files into the sandbox (which you could do via the File API and with drag-and-drop, keeping it an entirely client-side thing, no uploading required). But that isn't quite what you described.
No; this is not possible.
Javascript cannot directly interact with the user's local filesystem
No, it is not possible to access any of the clients files using JavaScript as that would be a security risk.